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arXiv · 1206.3163

Anomalous two peak structure in the Angle-resolved Photoemission Spectra of Ba1-xKxFe2As2

T. Shimojima·W. Malaeb·K. Ohgushi·A. Chainani·S. Shin·S. Ishida·M. Nakajima·S. Uchida·T. Saito·H. Fukazawa·Y. Kohori·K. Kihou·C. H. Lee·A. Iyo·H. Eisaki·K. Ishizaka
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Abstract

The electronic structure near the Fermi level (EF) of Ba1-xKxFe2As2 (BaK122 ; x = 0.2 - 0.7) is studied using laser ultrahigh-resolution angle-resolved photoemission spectroscopy(ARPES). For the optimally doped case of x = 0.4, we clearly observe two peaks below Tc in the ARPES spectra at a binding energies (BE) of 5 meV and 13meV. The former is assigned to a superconducting (SC) coherence peak since it appears and evolves below the bulk SC transition at Tc (= 36 K), accompanying a gap opening centered at EF. In contrast, the latter peak, which appears below ~ 90 K without any gap formation, is interpreted to be not directly related to a SC coherence peak. This high-BE peak is observed from x = 0.2 to 0.6, reduces in energy with overdoping (x > 0.4) and is absent for x = 0.7. The temperature(T)- and doping-dependent ARPES results suggest that the high-BE peak originates from coupling to a bosonic mode of energy ~ 8 meV.

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T. Shimojima, W. Malaeb, K. Ohgushi, A. Chainani, S. Shin, S. Ishida, M. Nakajima, S. Uchida, T. Saito, H. Fukazawa, Y. Kohori, K. Kihou, C. H. Lee, A. Iyo, H. Eisaki, K. Ishizaka. 2012-06-14. Anomalous two peak structure in the Angle-resolved Photoemission Spectra of Ba1-xKxFe2As2. https://arxiv.org/abs/1206.3163

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